Field of the Invention
The present invention relates to a tension measurement apparatus for testing electrical characteristics of semiconductor devices fabricated on a semiconductor wafer. More particularly, the present invention relates to a tension measurement apparatus for pogo pins in a pogo module arranged to contact a probe card when the electrical characteristics of semiconductor devices fabricated on a semiconductor wafer are tested.
Semiconductor devices such as transistors and integrated circuits are generally fabricated by repeatedly carrying out various processes such as oxidation, photolithography, etching, ion implantation, and the like to a wafer to form a given pattern thereon. However, as the elements incorporated into the semiconductor devices are increasingly integrated, unexpected defects are sometimes made in the semiconductor devices during the fabrication. To inspect the defects, an electrical die sorting (EDS) process is carried out as a post-treatment process.
In the EDS process, the electrical characteristics of semiconductor devices fabricated on the wafer are tested to decide if the devices are normal. A probe apparatus for finding out electrical characteristics of output signals to given input signals is generally used to inspect the devices.
The probe apparatus generally comprises a tester, a tester head, and a probe card which are sequentially disposed above a wafer to be tested. The wafer is held by means of a prober chuck. Between the tester head and the probe card, a pogo module is disposed. The pogo module functions to transmit electrical signals from the tester head to the probe card. For this, the pogo module has several hundred pogo pins disposed in a printed circuit board (PCB).
Each pogo pin comprises a housing disposed in the pogo module to penetrate the pogo module, needles disposed on both ends of the housing, balls disposed between the needles in the housing, and a spring disposed between the balls.
The spring of the pogo pin functions to provide a cushion between the tester head and the probe card when they are connected with each other through the pogo module. However, since the pogo pin is very fragile, it needs to be handled carefully. Also, according to the tension of the spring, the pogo pin may not correctly transmit the electrical signals to the probe card.
To inspect whether a pogo pin is normal, the pogo pin is tested for its external shape and tension. The external shape is generally inspected by eye. However, the tension must be inspected by means of a separate or portable tension measurement device. Conventionally, a portion of pogo pins as samples has been drawn out from the pogo module and then individually tested by means of the separate tension measurement device. Alternatively, a portion of pogo pins has been freely selected among pogo pins mounted in the pogo module and then manually tested by means of the portable tension measurement device.
The method of using the separate tension measurement device has an advantage in that it can correctly measure the tension of the pogo pin, however, it is inconvenient to draw out pogo pins to be used as samples from the pogo module. The convenience of using the portable tension measurement device is advantageous, but it is also problematic in that the force of pushing the pogo pin through the portable tension measurement device is not constant, thereby causing differing measurement results, i.e., the tension measurement can not be carried out under uniform conditions. Consequently, during the tension measurement, devices under test (DUT) can be damaged due to carelessness of an inspector. Also, a pogo pin may be damaged when it is pushed with excessive force by the portable tension measurement device.
Therefore, it is a feature of an embodiment of the present invention to provide a new tension measurement apparatus for pogo pins in a pogo module used in inspecting semiconductor devices to prevent inspection errors due to the pogo pins, in which the new tension measurement apparatus for pogo pins can correctly measure the tension of the pogo pins without having to remove them from the pogo module.
It is another feature of an embodiment of the present invention to provide a new tension measurement apparatus for pogo pins, which can measure the tension of pogo pins in a probe module under uniform conditions.
It is yet another feature of an embodiment of the present invention to provide a new tension measurement apparatus for pogo pins, which can easily measure the tension of pogo pins regardless of the position of the pogo pins mounted in a pogo module.
These and other features are provided, according to an embodiment of the present invention, by a tension measurement apparatus for pogo pins comprising a means for adjusting vertically a height to be measured, and a means mounted on the height adjusting means for measuring a tension of the pogo pin, wherein the means for measuring a tension of the pogo pin is vertically movable, according to the operation of the height adjusting means.
In a preferred embodiment of the present invention, the tension measurement apparatus further includes means for mounting the tension measuring means on the height adjusting means and moving it in a horizontal direction. The mounting and moving means comprises a vertical moving supporter mounted on the height adjusting means to be vertically movable according to the operation of the height adjusting means, a fixing member disposed to be connected with and separable from the vertical moving supporter, a moving rail rotatably connected to the fixing member, and a coupler for holding the tension measuring means mounted on the moving rail to be movable within the range of a given distance together with the tension measuring means.
The vertical moving supporter of the mounting and moving means may comprise at least one vertical support fixed to the height adjusting means, a horizontal support connected with a bottom surface of the vertical support, and a coupling projection formed on a side of the vertical support. The coupler of the mounting and moving means may comprise a latch plate for hanging and supporting the tension measuring means and a fixing plate for mounting the latch plate movably on the moving rail. Also, the fixing member of the mounting and moving means can comprise a connecting pin having a screw portion and a handle for rotating it, a connecting plate having a screw hole for receiving the screw portion of the connecting pin to be engaged therewith, and a body having a hole for receiving the connecting pin formed on one side thereof, a recess for receiving the connecting plate formed on a lower portion of the hole for receiving the connecting pin, and a penetration hole for receiving the coupling projection formed between the hole for receiving the connecting pin and the recess to fasten the fixing member to the coupling projection by the connecting pin and plate.
The moving rail of the mounting and moving means is rotatably connected to the fixing member through a rotating axis disposed on the other side of the fixing member and corresponding end of the moving rail. The rotating axis may comprise a locking pin having a screw hole formed in the center thereof, bearings for the fixing member and the moving rail inserted in circle shaped grooves formed respectively in the other side of the fixing member and the corresponding end of the moving rail, holes for receiving the locking pin formed respectively in the center of the circle shaped grooves, a ring disposed between the other side of the fixing member and the corresponding end of the moving rail, in which packings are inserted, and a screw for engaging with the screw hole of the locking pin.
Also, the moving rail is rotatable in a horizontal direction within a range of angles from xe2x88x92135 to +135 degrees. The moving rail is connected with an extended moving rail for extending a length of the moving rail in a longitudinal direction. For this, the extended moving rail preferably has the same cross or vertical section as the moving rail.
Also, the height adjusting means of the tension measurement apparatus comprises at least one vertical axis having scales formed in given intervals, a main body disposed to be movable along the vertical axis for measuring a distance moved from a standard position and displaying it, and a base for supporting the vertical axis.
The foregoing and other features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.